Well bore caliper



y 1960 E. L. GRONER ETAL 2,946,130

WELL BORE CALIPER Filed March 29, 1957 BATTERY STYLUS 56 MOTION MULJ' PLIER |l HI III' INVENTORS E DWARD L. GRONER,

AGENT LUTHER JOE HEKNOON, JR. Y

Unite WELL BORE CALIPER Filed Mar. 29, 1957, Ser. No. 649,352

Claims. (Cl. 33-178) This invention generally relates to internal calipering devices and more particularly relates to an improved well bore caliper featuring caliper feeler arm summation apparatus.

Completed well bores, when drilled by conventional rotary methods, are often inclined from the vertical and are of cross section other than circular. Thus, when well bore calipers are inserted into such holes the caliper tends to travel eccentrically relative to the well bore due to such inclination, and to have some of its feelers extended farther than others when the bore is of cross section other than circular.

Thus there is a need for a summation device with which the equivalent or mean diameter of such awell bore may be accurately determined by summation of the individual deflection of each feeler arm of the calipering tool.

Various approaches have been taken to accomplish this summation action, including both electrical and mechanical devices. Some of these have been reasonably successful, particularly those electrical devices provided with conventional well logging units. However, present mechanical devices, though averaging in a repeating manner, are usually non-linear in summation. Various hydraulic devices have also been devised. These, though linear in nature, are complicated and have leakage and fillage problems common to closed hydraulicsystems.

It is therefore an object of this invention to provide summation apparatus in combination with a well bore caliper which is simple, rugged, and purely mechanical.

It is another object of this invention to provide a well bore caliper tool suitable for isolated operation without outside source of power.

It is a further object of this invention to provide a well bore caliper of the type described having an improved feeler arm release means.

Briefly described, this invention consists of a caliper States ateit' 0 p IQC Other objects and advantages of the present invention will become evident from the following specific description taken in view of the accompanied drawing in which:

Figure 1 is an elevational view of the calipering tool when inserted in calipering position in a well bore.

Figure 2 is a plan view of the calipering tool shown in Figure 1.

Figure 3 is a longitudinal cross sectional view of the well bore caliper tool.

Figure 4 is a cross section taken at 4-4 of Figure 3.

Figure 5 is a cross section taken at 5-5 of Figure 3.

Figure 6 is a cross section taken at H of Figure 3.

Figure 7 is a cross section taken at 7-7 of Figure 3.

Figure 8 is a cross section taken at 88 of Figure 3.

There is shown in Figures 1 and 2 a caliper tool 10 inserted in a well bore 12. Extending from the body of tool 10 into contact with walls of well bore 12 are a plurality of caliper feeler arms 14a, 14b, and 140, generally designated herein as 14. Tool 10 is adapted to traverse well bore'12 from a steel measuring line 16 and hoisting apparatus 18. The speed of hoisting apparatus 18 may be varied to that required for operation of tool 10, as later described.

As shown in Figure 3, the feeler arms 14 of tool 10 may be held in retracted position by means of a latching assembly 20 attached to an extended support rod 22. Latch assembly 20 consists of a retainer sleeve or cup 24 attached to an actuating cylinder 26 containing an actuating spring 28 and a piston 30. Cup 24 and cylinder 26 are held in upward retaining position relative to piston 31} by a latching means, exampled as a pin 32. Whilein this latched position spring 28 is held in compression by extension of piston 30 into cylinder 26.

As herein illustrated, latch pin 32 is adapted to beremoved by means of an electrically detonated powder charge 34. Upon removal of latch pin 32, spring 28 is allowed to expand, thus retracting cup 24 from retention of caliper arms 14. Pointed out is that latching means 32 could be released by other means than powder charge 34. For example, latch pin 32 could be sheared between piston 30 and cylinder 26 by impact or spudding of tool 10 against the bottom of the well bore. Upon such shearing, cup 24 would then be urged to retracted position by spring 28, as previously described.

As seen in Figures 3 and 8, each of caliper feeler arms 14 is hinged to tool 10 in a manner permitting angular I movement of each arm out into contact with well bore tool having a plurality of caliper feeler arms adapted to provide linear longitudinal displacement to a transfer member in response to angular displacement of each of said feelers from said caliper body. The resulting longitudinal displacement of each transfer member is adapted to exhibit a linear and directly proportional force to a force responsive means. Said force responsive means is adapted to be deflected in direct proportion to the summation of those forces from said transfer members. A recording means is provided to record the deflection of said force responsive means as a function of the summated radial displacement of said feeler arms. When desired, a caliper arm retaining means may be provided in combination consisting of, a retaining cup adapted for radial retention of said caliper arms which will'release said caliper arms upon longitudinal movement of said cup relative to said caliper body, a latching means adapted toselectively hold said latching cup in a first longitudinal position relative to said caliper body, and spring means to urge said retaining cup through said releasing longitudinal movement relative to said caliper body. r

12. As illustrated, each of feeler arms 14a, 14b, and respectively pivots about a pin 36a, 36b, and 36c. Each of feeler arms 14 terminates at pin 36 with a cam 38. Each of said cams is provided of such profile to provide longitudinal motion to a push rod 40 as a linear function of the radial displacement of feeler arm 14 from tool 10. It is pointed out that the longitudinal position of each push rod 40 will then be a predetermined function of the angular position of its respective feeler arm 14. Locations of these push rods 40 are designated at 40a,'40b, and 40c in Figure 7. a V

It is pointed out that, though only three caliper feeler arms 14, herein designated as 14a, 14b, and 14c, are herein illustrated and described, any larger number of such feeler arms may be provided. The only limitation would be that imposed by the dimensions of a specific tool10. Under certain conditions, it sometimes maybe desirable to employ a larger number of such feeler arms.

Each of push rods 40 is provided in moveable but spring loaded relation with a floating deflection plate 42. As illustrated, each rod 40 extends through plate 42 and is held in spring loaded relation by means of a spring 44 compressed by a retainer 46. Deflection plate 42 and each. of springs 44, designated as 44a, 44b, and 440, are further illustrated by sections shown in Figure 5 and in Figure 6.

Deflection plate 42 is balanced against the forces from springs 44 by the force exerted by the loading of a spring 48. Attached to deflection plate 42 is a deflection transfer rod 50 extending into mechanical connection with a motion multiplying means, 52. Spring 48 and transfer rod 50 are further illustrated by a section shown in Figure 4.

Extending from multiplying assembly 52 is a recorder arm 54, terminating in a recorder stylus 56. Stylus 56 is adapted for moveable contact across a recorder chart 58. Recorder chart 58 is driven at a constant and predetermined speed through a chart drive 60 by a clock motor 62, herein exampled asbein'g a battery powered electric motor. Motor 62 is powered by a battery 64. When provided as illustrated, the speed of motor 62 and the gear reduction of chart drive 60 is such that chart 58 moves past stylus 56 at a desired predetermined and constant rate of displacement, six inches per minute being an example.

Also connected into chart drive 60 is a cam operated switch 66, which is adapted to close after a desired pre determined running period of clock motor 62. Battery 64 is electrically connected through switch 66 to powder charge 64 which is provided to be detonated upon the closing of said switch. As conveniently illustrated, powder charge 34 is shown having connection through support rod 22 and the wall of tool to switch 66 and battery 64.

Cam switch 66 is positioned such that it will be initially open and will subsequently close after a desired predetermined interval, usually determined by that time necessary for tool 10 to reach the depth in well bore 12 where a calipering operation is to begin. Such a time period may be about 30 minutes, for example.

As shown, deflection plate 42 is held in balanced position by the forces exerted by springs 44 in opposition to the force exerted by spring 48. It is seen that, if any of springs 44 were to exhibit a greater or lessened force, deflection plate 42 would shift to such position necessary to cause an equal and opposing force to be exerted by spring 48. An angular deflection of caliper feeler arm 14 will cause corresponding longitudinal movement of push rod 40 and deflection of spring 44. Being of linear characteristic the. change in deflection of spring 44 will cause a corresponding change of force exerted against plate 42, thus causing the previously described shifting of plate 42 to achieve a rebalance of forces.

It is pointed out that, if all of caliper arms 14 were initially at an equal angular position and one of such caliper arms were to be extended in an amount equal to the retraction of a second caliper arm, the extension said arm would lessen the force on plate 42 and the retraction of said second arm would increase the force on plate 42. Thus, if such arms were to have angular movement equal and opposite, the net change or summation of forces at plate 42 would be zero.

For use of the invention as illustrated, tool 10 is lowered by means of hoisting reel 18 into well bore 12 to the desired depth, from which a record is desired. Tool 10 is then poised at this level for sufficient time to allow cam switch 66 to close and cause firing of powder charge 34. Upon such detonation, latch pin 32 is forced from retainer assembly 29. Spring 28 thereupon urges retainer cup 24 into a lowered position, allowing caliper feeler arms 14 to extend into contact with the well bore wall. If latch pin 32 is alternatively provided to be sheared rather than removed by charge 34, this opening operation may be performed by spudding tool 10' against the bottom of well bore 12.

Upon release of caliper feeler arms 14 and their subsequent angular extension into contact with the well bore wall, each of push rods 40 will be proportionally displaced in longitudinal movement in response to the face position of cam 38 presented by such angular position. The displacement of push rod 40 caused by extension of feeler arm 14 then causes a change in deflection of spring 44. Such deflection change in turn causes a proportional change in force to be exerted against deflection plate 42. To then balance such force change, the opposing force from spring 48 is also changed by a responsive deflection of said spring. This rebalancing of opposing forces on plate 42 causes small displacements of such plate in the establish ment thereof. This small displacement of plate 42 is then transferred through transfer rod 50 into the recording section of tool 10.

Since the movement of transfer rod 50 will of necessity be quite small, such movement is multiplied by motion multiplier 52, herein exampled as a rack and pinion assembly, and transferred through recorder arm 54 to stylus 56. When provided as illustrated, the multiplication factor of multiplier 52 is such that stylus 56 will fully traverse chart 58 upon extension of all the caliper feeler arms 14 from a fully retracted to a fully extended position.

As caliper tool 10 traverse a well bore 12 of varied diameter, the extension of the caliper feeler arms 14 varies in response. Thus, each caliper arm individually places a force on deflection plate 42 in response to its respective extension. The forces thus exerted on plate 42 are summed into an individual deflection of spring 48, and the position thus established by plate 42, upon the balance of such forces is indicative of the summated radial displacement of all the caliper feeler arms 14.

Such summated position is then linearly multiplied by multiplier 52 and recorded on chart 58 by stylus 56.

It is pointed out that any excursion of stylus 56 on chart 58 from the initial closed position of caliper tool 10 will be representative of the equivalent or mean diameter of well bore 12 at a particular point. Such record would be essentially accurate even when caliper tool 10 is eccentrically positioned relative to well bore 12, as indicated in Figure 2, or when well bore 12 is of cross section other than circular.

It is also pointed out that, as herein illustrated, caliper tool 10 may be an integral device requiring no outside source of power or recordation and may be transported and used from the commonly available steel measuring lines found at any well here drilling rig.

It is apparent that other modifications and variations of the present invention, as herein illustrated and described, may be made without departure from the spirit and scope thereof, and therefore limitations should be imposed only as are indicated in the appended claims.

That being claimed is:

1. A caliper tool adapted to determine variations in effective diameter within a well bore comprising; a plurality of caliper feeler arms adapted to angularly extend from said tool into contact with a well bore wall; each of said feeler arms in direct coupling with a resilient force inducing means, each of said feeler arms adapted to linearly displace. its respective force inducing means to induce a force of magnitude directly responsive to the radial displacement of the respective feeler arm; a deflection means connected in force transmitting coupling with said force inducing means; a resilient force opposing means connected inforce transmitting coupling to said deflection means. adapted to impose an opposing force equal to the summation of forces of said feeler arm force inducing means and be deflected in linear relation to the magnitude of said opposing force, said deflection means adapted to be displaced in direct response to the deflection of said force opposing means; displacement indication means to indicate the displacement variation of said deflection means; and releasable means to initially retain said feeler arms in retracted position.

2. A caliper tool suitable for mean diameter determination within a well bore comprising; a plurality of caliper feeler arms adapted to angularly extend from said tool into contact with a well bore wall; a respective force inducing means in direct coupling with each of said feeler arms, each of said force inducing means adapted to be deflected in linear relation to the radial displacementof its respective feeler arm and induce a force in relationtto such deflection; a deflection means in direct conplingwith said force inducing means of said feeler arms; a resilient deflectable force opposing means connected in direct coupling to said deflection means, said force opposing means adapted to impose an opposing force of magnitude equal to the sum of forces of said feeler arm force inducing means and to deflect in linear response to the magnitude of said opposing force, said deflection means adapted to be displaced in direct response to deflection of said force opposing means; displacement indication means connected to said deflection means, said indication means adapted to indicate the displacement of said deflection means as a function of the sum of the extended displacements of the respective feeler arms from said tool; and a feeler arm retaining means connected to said tool adapted to initially retain said feeler arms in retracted position.

3. A caliper tool adapted to determine variations in eflective diameter within a well bore comprising; a plurality of caliper feeler arms adapted to angularly extend from said tool into contact with a Well bore well; each of said feeler arms in direct coupling with a resilient force inducing means, each or" said feeler arms adapted to linearly displace its respective force inducing means to induce a force of magnitude directly responsive to the radial displacement of the respective feeler arm; a displaceable deflection means in force transmitting coupling with said force inducing means of said feeler arms; a resiliently deflectable force opposing means connected in force transmitting coupling to said deflection means adapted to impose an opposing force equal to the summation of forces of said feeler arm force inducing means, said deflection means adapted to be displaced in direct. response to the deflection of said force opposing means; and displacement indication means to indicate the displacement variation of said deflection means.

4. A caliper tool suitable for mean diameter determination within a well bore comprising; a plurality of caliper feeler arms adapted to angula-rly extend from said tool into contact with a well bore wall; a respective resilient force inducing means in direct coupling with each of said feeler arms, each of said feeler arms adapted to impose a linear deflection on its respective force inducing means to induce a force in direct response to the radial displacement of the respective feeler arm; a displaceable force balance means in direct coupling with said force inducing means of said ifeeler arms; a resilient force opposing means connected in direct coupling to, said force balance means, said force opposing means adapted to impose an opposing force of magnitude equal to the sum of forces of said feeler arm force inducing means and to deflect in linear response to the magnitude of said opposing force, said force balance means adapted to be displaced in direct response to deflection of said force opposing means; and displacement indication means connected to said force balance means, said indication means adapted to indicate the displacement of said force balance means as a function of the sum of the extended displacements of said feeler arms from said tool.

5. A mean diameter caliper tool comprising; a plurality of caliper feeler arms linked to said tool for angular extension into contact With a well bore wall; a plurality of resilient force inducing springs each in direct coupling with a respective feeler arm; each of said feeler arms adapted to deflect its respective force inducing spring to produce a force of directly linear relation to the radial displacement of said feeler arm; a displaceable deflection plate in direct coupling with each of said force inducing springs; a resilient force opposing spring connected in direct coupling to said deflection plate; said force opposing spring adapted to impress an opposing force on said deflection plate of magnitude equal to the sum of forces of said force inducing springs and to deflect in directly linear response to the magnitude of said opposing force; said deflection plate adapted to be displaced a distance equal to the deflection of said force opposing spning; and displacement indication means connected to said deflection plate for indicating the displacement of said deflection plate as a function of the sum of the radial extensions of each respective feeler arm.

References Cited in the file of this patent UNITED STATES PATENTS 2,102,080 Kinley Dec. 14, 1937 2,340,987 Robidoux Feb. 8, 1944- 2,4l5,636 Johnson Feb. 11, 1947 2,660,800 Wiley Dec. 1, 1953 2,680,913 Johnston et *al. June 15, 1954 2,719,362 Montgomery Oct. 4, 1955 2,725,486 Wal-strom Nov. 29, 1955 

